Build messageformat against the SDK and not the platform.
It builds entirely against public API, so there's no reason to
build against the platform. This makes it safe for use from
applications.
(cherry picked from commit 8ffc099ee3996e65fbff658b3942b59e4b6ac8c5)
Change-Id: Ie94c5ec38688833ec3a8f1374e56482fdc94037a